Supplement: Metalloendocrinology: Mapping Bioinorganic Chemistry in the Extracellular Space

项目摘要

PROJECT ABSTRACT Copper is an essential micronutrient in biology, playing fundamental roles in processes such as respiration and antioxidant defense. The context in which a copper ion resides is vital to its activity, and its miscompartmentalization and imbalances is associated with a host of disorders. While technologies have emerged to investigate intracellular copper dynamics, the extracellular copper pool is relatively under- characterized. The parent grant of this supplement seeks to elucidate the speciation of metals in the extracellular space, with a focus on the interplay of metals with another dynamic component in the extracellular environment, hormones. The main research of this objective focuses on a particular peptide with hormone-like functions, C- peptide, a 31-mer derived from the proinsulin protein. Historically undervalued as an innocent secondary marker for insulin, C-peptide is of increasing interest for its bioactivity independent of insulin. However, its advancement has been hampred by lack of mechanistic understanding. Work under the parent project has shown that C- peptide can directly bind to copper, an event that can modulate C-peptide's activity. In Aim 1 of this proposal, we seek to determine whether and how C-peptide and its truncates affect copper trafficking. Preliminary work suggests that the metal-binding interaction can shift the homeostatic balance of the metal. A combination of in vitro and in vivo work will seek to analyze the pathways that drive the interplay between C-peptide and copper. Aim 2 seeks to leverage the interactions of copper and C-peptide to identify a plasma membrane receptor for the peptide. While an orphan GPCR, GPR146, has been proposed as a partner for C-peptide, this claim remains debated. We hypothesize that metal interactions with the peptide, which is rich in negatively-charged residues, may be influential in receptor recognition. This aim will screen for C-peptide interactions with a library of orphan GPCRs in the presence and absence of transition metals to determine whether metals are integral to receptor recognition, and if so, identify a cognate receptor for the peptide. To achieve these research goals, the candidate to be supported by this supplement will be trained across disciplines with a multifaceted mentoring team to bring molecular insight to metalloendocrinological processes.